1. Field of the Invention
The present invention relates to an air-conditioner for automobiles of the type including a cool air bypass unit capable of controlling the temperature of an upper part of the vehicle passenger compartment in the vicinity of the head of an occupant, wherein a complex control of the operation of various components of the air-conditioner is performed according to the head part setting temperature so as to improve the feeling of comfort of the occupant.
2. Description of the Prior Art
There are known automobile air conditioners which include a cool air bypass system having a cool air outlet provided in addition to heat, vent and defroster outlets for cooling of the occupant's face during the heating operation, thereby keeping the head cool and the feet warm. Attempts have been proposed to automatically drive a cool air bypass door under certain conditions for improving the feeling of comfort of the head part of the occupant. According to one such known proposal disclosed in Japanese Patent Laid-open Publication No. 63-34216, the cool air bypass door is driven to force cool air against the head of the occupant when two conditions are fulfilled, i.e. when the temperature of discharged air is higher than a predetermined level and the difference between the temperature of the passenger compartment and the setting temperature is greater than a predetermined level.
Japanese Patent Laid-open Publication No. 58-33509 discloses an attempt to improve the feeling of comfort of the head portion of the occupant without using the cool air bypass system. According to this attempt, the portion of an air-flow duct disposed downstream of a blower is separated into at least two air-flow passages and an air-mix door is provided in each of the air flow passages so that the conditioned air is discharged from the respective air-flow passages into two different portions of the vehicle passenger compartment.
In the conventional cool air bypass system disclosed in the first-mentioned Japanese Publication, the opening and closing operation of the cool air bypass door is unable to produce changes in temperature and flow rate of discharged air which are large enough to change the feeling of the head part of an occupant. The prior attempt disclosed in the last-mentioned Japanese publication is not satisfactory to provide a desired comfortable feeling even when a head part temperature setter is provided for controlling the temperature of the head part of the occupant. Further, the latter attempt is complicated in the structure.